Viessmann VITODENS 100-W Installation And Service Instructions Manual page 60

Troubleshooting
Fault messages
(cont.)
Displayed fault System characteristics
code
468 Burner in a fault state
471 No heat demand
474 Burner in a fault state
517 Normal operation, remote
control unit not functioning
527, 528 Burner in a fault state
60
Cause
Ionisation current too high
during calibration
System pressure sensor
not available, lead break
or short circuit
Error in scheduled pro-
gram run monitoring
Lead break, PlusBus ca-
ble, incorrect appliance
address set, remote con-
trol faulty
Incorrect HBMU heat
management unit parame-
ter set
Measures
Check gap between ionisation
electrode and burner gauze as-
sembly.
Check whether there is a lot of
dust in the ventilation air (e.g. from
construction work).
Reset the appliance.
Note
Deposits on the electrodes indicate
foreign bodies in the ventilation air.
Check the installation room and
flue system for causes of the de-
posits. For example: Laundry de-
tergents, cleaning agents, toilet-
ries, deposits in the ventilation air
supply (chimney).
If burner gauze assembly and ioni-
sation electrode have been re-
placed, also clean fan unit, gas/air
channel and Venturi extension.
Check system pressure sensor
■
(plug ).
aND
Check lead and plug-in connec-
■
tion.
Measure the supply voltage to
■
the sensor to see if it is 5 V
Reset the appliance.
If the fault occurs repeatedly, re-
place the HBMU heat management
unit. See chapter "Replacing the
HBMU heat management unit".
Check the setting in the commis-
■
sioning assistant. Correct if nec-
essary.
Check remote control cable.
■
Check remote control subscriber
■
number. Replace faulty remote
control if applicable.
Overwrite (flash) the HBMU heat
management unit with the correct
parameter set.
.
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